1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to a home network, and more particularly, to sharing secret information between devices in a home network.
2. Description of the Related Art
Many industrial standard associations such as digital living network alliance (DLNA), home audio-video interoperability (HAVi), and universal plug and plug (UPnP) have actively researched home network technologies.
A remote user interface (RUI) technology for allowing one device to control functions of other devices is used in home networks. The RUI technology is based on a client-server architecture. In the RUI technology, an RUI client fetches a user interface (UI) from an RUI server, and a user controls the RUI server through the UI on the RUI client.
In a home network environment, the user can use an e-commerce service, a home shopping service, or the like through the RUI. Security vulnerability of the current RUI technology may cause the risk of exposure of important personal information such as social security numbers or credit card numbers to an attacker. For example, when protocol stacks for a home shopping service are provided through only an RUI supporting settop box, a user fetches the RUI of the settop box for an RUI supporting TV so as to use the RUI for the home shopping service. At this time, important personal information may be transmitted and received between the TV and the settop box, and the personal information may be exposed to an attacker existing in the home network. Therefore, a method of securely transmitting and receiving messages between home network devices is required. Accordingly, it is important to share secret information such as a session key between the home network devices without exposure to the attacker.
FIG. 1 is a view illustrating a man-in-the-middle (MITM) attack in a remote desktop protocol (RDP).
As shown in FIG. 1, a client that attempts to access a server is unknowingly made to access an attacker's device with domain name service (DNS) spoofing, address resolution protocol (ARP) poisoning, or the like. Initially, the server and the client attempt to exchange random numbers Rs and Rc for generating a session key. At this time, the attacker intercepts a public key and the random number Rs of the server and transmits a fake public key P encrypted with another random number Rs′ to the client. The client accepts the fake public key encrypted with the random number Rs+ as a true public key of the server and transmits the encrypted random number Rs. The attacker acquires the random number Rc of the client by decrypting a message transmitted from the client and transmits the random number Rc encrypted with the public key to the server. As a result, the attacker can sniff all the messages between the server and the client.
In order to prevent the attack, in a public key infrastructure (PKI), a certificate is used to determine whether or not the public key of the server is fake. However, in the case of using the certificate, a certificate authority is required. In addition, in the client, a process for authenticating the certificate involves a large amount of calculation, which results in a burden on the home network. Therefore, there is a need for a method of securely sharing secret information between home network devices with a small amount of calculation without any certificate.